Acceptance required question

I’m trying the acceptance option where the visitor needs to tick the box. It seems to work fine except if I enter my details and don’t tick the box there isn’t any error displayed when clicking the submit button so nothing happens. If the acceptance is underneath the submit button and especially on a mobile device people might not scroll past the submit button so not realise it’s there and that they need to tick it. If I’m not missing something, is there a way to show an error message or something so people realise it’s there? Thanks.